This invention is an improvement in the shutter mounting clamp disclosed in U.S. patent application Ser. No. 366,882, filed on June 4, 1973, now U.S. Pat. No. 3,868,803. This patent discloses a plastic shutter which has a pair of spaced-apart vertical mounting channels attached to its rear side portions. The shutter is attached to a building wall beside a window frame by means of U-shaped clamps which are nailed to the wall in position to engage the mounting channels and hold the shutter in the desired position relative to the window. These prior art mounting clamps perform their intended function, but they are relatively difficult to install because their position must be carefully measured relative to the window frame and relative to each other so that they will match the spacing of the mounting channels on the shutter and will hold the shutter in the correct spacing and alignment relative to the window frame.